photo-, phot-, -photic

(Greek: light; ultraviolet and infrared radiation; radiant energy)

phototherapy
1. The treatment of disease, e.g., herpes simplex, psoriasis, neonatal hyperbilirubinemia, or seasonal affective disorder, by exposure to light; especially, by variously concentrated light rays of specific wavelengths.
2. The use of ultraviolet radiation in the treatment of skin deseases.
photothermal
A reference to the heat produced by radiant energy.
photothermic
1. Related to radiant heat.
2. Pertaining to the heating effect of light-rays.
photothermy
Involving both light and heat.
phototonus
The sensitivity of an organism to light.
phototopia
Vision with eyes that are adapted to normal bright daylight.
phototoxic
1. Capable of rendering the skin abnormally sensitive to light.
2. Pertaining to, characterized by, or producing phototoxicity.
phototoxicity
The property of rendering the skin abnormally sensitive to light.
phototoxins
Chemically induced kind of photosensitivity which when in drugs and cosmetics, can react with sunlight to produce mild rashes or burns, severe headaches, or nausea and vomiting.

These ingredients can cause problems even when a strong sunblocker is used.

phototoxis
The condition resulting from damage by light.
phototroph
An organism that uses light for its energy needs.
phototrophic
Capable of deriving energy from light, as in certain green plants and bacteria.
phototropic (adjective)
The growth response of plant parts to the stimulus of light, producing a bending towards the source of light.
phototropism (s) (noun)
1. The growth, or movement, of a part of a plant in the direction of or away from light sources.
2. The tropism (movement) of an organism in response to the source of a light stimulus.
3. The change of color produced in a substance by the action of light.

A mother is yelling at her daughter, to get down from a tree and the daughter says to her companion, "She doesn't believe kids should manipulate a plant's natural phototropism to create organic arboreal habitats."

—As seen in a cartoon titled "Baldo" by Cantu and Castellanos
in the Stars and Stripes "Sunday Comics" section; July 20, 2008; page 3.
photovoltaic (PV)
1. Employing the photoelectric effect; that is, the production of electric power from electromagnetic radiation.
2. Relating to, or designating devices that absorb solar energy and transform it directly into electricity.
3. Able to generate a current or voltage when exposed to visible light or other electromagnetic radiation.

Etymologically related "light, shine, glow" word families: ethero-; fulg-; luco-; lumen-, lum-; luna, luni-; lustr-; phengo-; pheno-; phospho-; scinti-, scintill-; splendo-.